Exercise bicycle



FIG. 1 is a front perspective view of an exercise bicycle showing our new design;

FIG. 2 is a rear perspective view thereof;

FIG. 3 is a side elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a front elevational view thereof; and,

FIG. 6 is a top plan view thereof. 

The ornamental design for an exercise bicycle, substantially as shown and described. 